1. Field of the Invention
The present invention relates to a digital versatile disk (DVD) technology, and more particularly, to a method for formatting and interleaving error correction blocks adaptively for improving a capability of correcting short burst errors in a high density DVD.
2. Description of the Related Art
In general, DVDs are largely categorized as two types; read only DVDs and read and rewritable DVDs. The information storage on a read only type optical disk is realized by forming grooves called pits on the surface of the disk, “0” is assigned to represent a pit portion, and “1” is assigned to represent a non-pit portion (that is, a land). During reproduction, a laser is irradiated onto tracks of the disk, and “0” and “1” are distinguished according to a difference in the light reflectivity. For example, in a rewritable-and-erasable phase-transition optical disk, a recording layer of the disk undergoes structural transformation between crystalline and amorphous states by the heat generated from the laser. There are significant differences between the reflectivity of these two states, which correspond to “1” and “0”, respectively. The recording layer can be selectively changed into either a crystalline state or an amorphous state by adjusting the power of a laser during recording.
Errors generated at a DVD disk include random errors occurring to all channels, short burst errors due to dust or foreign matter, long burst errors due to scratches, or the like. To correct such errors, a conventional DVD error correction system employs a Reed-Solomon Product code. For example, in a digital versatile disk recorder (DVDR) having a storage capacity of 4.7 GB, in order to reduce correlation between adjacent data of data blocks, scrambling is performed on data blocks, and 16 sectors constituting each data block are grouped into a size of 12×172 bytes to form a data block of 192×172 bytes, as shown in FIG. 2. Then, RS (208, 192, 17) encoding is performed in a column direction to generate an outer code parity of 16 bytes (PO), and RS (182, 172, 11) encoding is performed in a row direction to generate an inner code parity of 10 bytes (PI), thereby forming a 208×182 byte ECC block.
After obtaining the ECC block in such a manner, row interleaving is performed such that each PO portion is interleaved for every 12 rows, that is, at the end of the last row of each sector, as shown in FIG. 3. According to the conventional interleaving method, data can be transmitted in a uniform transmission rate, but error correction is completely dependent upon ECC cores, that is, an RS codec (PI and PO).
In order to attain a high density DVD, a laser spot of a DVD must be reduced to approximately a half that of a conventional DVD and a numerical aperture (NA) of a lens must be increased to make a transparent film of a laser incident plane thinner. Thus, foreign matter causing short burst errors, such as dust, or a scratch causing long burst errors, is relatively increased, thereby disabling from carrying out error correction processing using a conventional error correction system.